When running my mirror, I want to put the database on a separate more powerful machine, where I have separately configured the username/password for the musicbrainz database.

I'd like to be able to specify the configuration for this database by using environment variables. I see that it's already possible in DBDefs for the username and password, but not for the database name or database host.

Additionally, the index script for the indexer image hard-codes these values instead of being able to specify them as arguments or environment variables.